Due to the huge size and weight of off-road or construction working machines, and functions such machines need to perform while in the field, such off-road or construction machines are generally well equipped with an hydraulics system to control various operations of the machine such as digging, excavating, loading, hammering, compaction etc. as well to provide power to various auxiliary or additional service equipment used in such machines, such as attachments for excavators or loaders.
The hydraulic system is further utilized in earthmoving or construction working machines to convenience an operator to control various functions and also to provide better safety to the operator and people working around the machine.
The typical earthmoving or construction equipment includes a hydraulic system having one or more hydraulic pumps. Various hydraulically operated services are linked with the hydraulic pump. One or more pressure relief valves or control valves are used to control the supply of hydraulic fluid from the hydraulic pump to fluid pressure lines used for various operations. These pressure relief valve or control valves are controlled by the operator via a joystick or dashboard or any other actuating means. Thus machine operation may use a control interface to control operation of the one or more control valves to cause actuation of one or more of the actuators. The actuators are used for controlling various operation and parts of machine.
The hydraulic pump is used for circulating pressurized hydraulic fluid across various fluid circulation lines to perform various mentioned service operations. The standard corresponding fluid pressure is required throughout these lines to perform such operations. However, if there has been the least little pressure drop across the pressure line it can cause an operation to stop or stall. There may be the possibility that the hydraulic pump has become disabled or is not operating.
Conventionally the earthmoving or construction machine is equipped with above mentioned hydraulic system. However, pressure of hydraulic fluid is controlled by the operator through the joystick or any other manual means. It is often observed that a machine operator has to perform two or more tasks simultaneously while working on a machine. A machine operator will need to control the pressure of one or more hydraulic pumps at a time. Whenever the hydraulic pump gets stalled, disabled or is not operating because of overloading or lack of hydraulic fluid in the pressure line, the machine operator has to regulate control valve or relief valve through the joystick or any other manual means.
For example, when the working machine is a compactor, the operator will need to control the pressure of one or more transmission or travel pumps to control movement of the machine, and at the same time control the pressure of a service pump that drives the vibration means. It can be difficult to maintain a suitable pressure in all of the pumps simultaneously, so it is easy for the operator to cause the engine to stall. In particular, it can be difficult for an inexperienced operator to maintain a suitable pressure in all of the pumps simultaneously. It is difficult to determine whether a suitable pump pressure is maintained, so that the first indication given of pressure in one of the pumps becoming too high is likely to be the engine stalling. This is undesirable as it places unwanted strain on the engine and potentially on the transmission and the hydraulic system, which can cause damage or increase the need for maintenance.
In order to overcome the stalling effect due to the hydraulic pump system being disabled or not operating because of overloading, it is more desirable to have a method for controlling an engine stall which is simple in construction, effective and cost effective than previously known methods and solves or at least relieves some of the problems discussed above.
It is therefore an object of the present invention is to overcome one or more problems associated with the prior art.
Further advantageous embodiments and further advantages of the invention emerge from the detailed description below.